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Tyrrell_McAllister comments on Book Review: Naive Set Theory (MIRI research guide) - Less Wrong Discussion

13 Post author: David_Kristoffersson 14 August 2015 10:08PM

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Comment author: Tyrrell_McAllister 15 August 2015 03:24:01PM *  4 points [-]

There is a convention according to which a one-to-one function is injective, while a one-to-one correspondence is an injective function that is also surjective, ie, a bijection. (I don't know whether Halmos uses this convention.)

Comment author: gjm 15 August 2015 03:55:11PM 0 points [-]

Oh yes, for sure, but the context here was a statement that "onto" means surjective while "one-to-one" means bijective. Definitely talking functions. And I would be really surprised if Halmos were using "one-to-one" followed by anything other than "correspondence" to mean bijective.

Comment author: David_Kristoffersson 16 August 2015 09:53:22AM 0 points [-]

You guys must be right. And wikipedia corroborates. I'll edit the post. Thanks.